Studies are centered in three areas involving interactions between proteins and DNA: (a) The in vitro and in vivo function of omega type proteins. Protein omega from E. coli has been purified to homogeneity and appears to be a swivelase in vitro. Purification of a similar protein from Drosophila eggs is under way. Further physicochemical and enzymological studies of these proteins will be carried out. More mutants are to be screened to elucidate the in vivo function of omega in E. coli. (b) The unwinding of the DNA helix by proteins. Studies on the unwinding of the DNA helix by transcription, and the possibility of unwinding of the DNA helix by proteins involved in negative and positive control, are being continued. (c) The terminal generating enzymes of temperate phages. The sequence recognition problem involved in the generation of the cohesive ends of lambodoid phages and phages of the P2 family is being investigated.